<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>浮动定位</title>
  <style>
    body>div{
      width: 200px;
      /*height: 200px;*/
      border: 1px solid red;
        overflow: hidden;

    }
    #d1{
      width: 50px;
      height: 50px;
      background-color: red;
      float: left;
    }
    #d2{
      width: 50px;
      height: 50px;
      background-color: green;
      float: left;
    }
    #d3{
      width: 50px;
      height: 50px;
      background-color: blue;
      float: left;
    }
  </style>
</head>
<body>
<div>
  <div id="d1"></div>
  <div id="d2"></div>
  <div id="d3"></div>
</div>
</body>
</html>